Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Adds substantial behavior beyond the annotations: credit spend per clip, the rule that a clip which cannot start is not charged, the async task-id model with get_task as the polling sibling, and the fact that output is unjoined clips. These are exactly the side-effect and output facts an agent needs and the annotations do not carry.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Four tight sentences, front-loaded with the chaining definition, then cost, then return/next-step, then output shape. No sentence is redundant with another and none restates the tool name.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description still covers the return contract (task id, retrieve URLs via get_task, separate clips) and the billing model. Combined with a fully documented schema, an agent has everything needed to invoke and follow up correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the baseline is 3, but the description adds real semantic value by explaining how initial_frame_uri relates to the scenes array (it seeds the first clip) and that scenes are ordered and chained, which the schema structure alone does not convey.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource plus the defining mechanism: 2-8 clips where each starts from the last frame of the previous one. This clearly separates it from sibling generate_video (single clip) and compose_scene without requiring the schema to be opened.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives clear operational context (first clip seeds from your image, check progress with get_task, output is separate clips not a joined file). It never explicitly says when to prefer this over generate_video or compose_scene, so it stops short of full alternative routing.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.